BOISE, Idaho (AP) Kellen Moore brushed it off as just a doctor thing. Chris Petersen was even more evasive about the black knee brace Boise State's star quarterback sported on Saturday night.

"Kellen watches a lot of TV and when Andrew Luck and Landry Jones wear the knee braces now he wants to be in the club," Petersen quipped. "That's all I think that was about."

The truth is while the fourth-ranked Broncos (3-0) rolled through their first month of the season, they head toward October with a number of potentially concerning injuries.

Moore is seemingly the most noticeable thanks to the bulky brace that was hard to miss during the Broncos' 41-21 win over Tulsa on Saturday night. Moore seemed unfazed, throwing for four touchdowns in less than 2 1/2 quarters. Yet anytime Moore had to scramble from the pocket - which was rare - his gait was off, jogging back to the huddle with a slight limp.

Moore acknowledged he was a bit "banged up" after the Broncos beat Toledo a week earlier and that part of the reason he might have departed after throwing a 10-yard TD pass to Mitch Burroughs on Boise State's first drive of the second half was due to his sore knee. Backups Joe Southwick and Grant Hedrick finished off the Broncos' 33rd straight regular season home victory.

"Maybe a little bit. It's good to get Joe some experience and got Grant in there as well," Moore said. "Down the road they're going to make some big time plays here and they have to get some experience."

Boise State just hopes down the road is 2012.

Knee problems weren't limited to Moore. Center Thomas Byrd saw his string of 36 consecutive starts end when he didn't even suit up. Byrd has battled chronic knee problems and missed most of spring practice to give his knees a break. Byrd has now started 41 of 43 games since the beginning of 2008.

For most of the night, Boise State was down two starters on the offensive line from the group that started the opener against Georgia. Along with Byrd sitting out, the Broncos saw right guard Jake Broyles go down in the first half Saturday with a leg injury and not return.

The shuffle of the offensive line could be part of the reason Boise State's running game continues to underperform. It was one of Petersen's biggest concerns coming out of Saturday night after the Broncos managed just 131 yards on the ground. Starter Doug Martin had 75 yards on 21 carries, but 14 of those carries were for 3 yards or less, including six runs for no gain or a loss.

The Broncos averaged just 2.9 yards per rushing attempt.

"I think this team is capable with the line that we have and the backs that we have," Petersen said. "We need to be able to run the ball better."

The injury concerns aren't just offensive. Defensive lineman Chase Baker suited up but didn't play with an undisclosed injury. Then the Broncos saw defensive linemen Tyrone Crawford and Billy Wynn each lying on the field in significant discomfort in the second quarter with apparent leg injuries. Each had to be helped off the field, putting little weight on their injured legs and both seemed destined for an early night.

But both were back out for the first series of the second half, allowing the Broncos at least one good injury sign.

"It's football season. You're going to have to play with some bumps and bruises," Petersen said. "But that's why we worry so much because we know how fast things can change. You can see that if Billy and Tyrone go down with those other guys out, it's paper, paper thin, we almost don't have enough guys. We just keep our fingers crossed that we can stay healthy here as the season goes on."